The protective and insulating capabilities of wearable articles, including footwear, are important considerations depending on the intended use of such wearable articles. As an example, manufacturers have adapted footwear to perform based on potential outside conditions that the footwear is to be exposed to provide better comfort and protection for a user. For example, cold-weather footwear may be designed to retain or maintain heat and protect a user's foot from cold and/or wet conditions. Exterior protective layers and internal linings have been used to attempt to retain heat within such footwear.
However, in known cold-weather footwear, heat loss may occur through radiation and conduction of heat from the wearer's foot to the cold, exterior surfaces in contact with the footwear. For example, the outsole of the footwear may conduct heat to exterior surfaces of the footwear. In some examples, such exterior surfaces may be exposed to the elements and may be covered in ice and snow. In conventional cold-weather footwear, various insulating layers with lofted air may be used to attempt to reduce heat transfer. However, positioning lofted airspace in the insole and/or midsole in such footwear results in excessive compression due to the wearer's weight, thus decreasing the lofted airspace and effectively eliminating the insulating ability of such layers during wear.
In one approach, described in U.S. Patent Application Publication 2006/0130367, a heat insulating lining is described with a porous layer disposed between two reflective layers which are vacuum sealed in an enclosure body. The porous layer comprises an elastic material, while the reflective layers comprise a metal having low conductivity. Further, a foam layer, comprising an elastic cushioning material, may be disposed outside of the vacuum sealed enclosure. During use, heat radiation is impeded by the reflective layers and conduction is inhibited by the vacuum of the sealed enclosure body.
The inventors herein recognize potential issues with the above vacuum configuration. As one example, vacuum sealing may degrade over time, and thus loss of the vacuum may result in loss of the insulating ability of the footwear. As another example, even if the vacuum is maintained over the life of the footwear, the lack of heat capacity of the vacuum layer reduces its ability to store heat. For example, even if radiated heat is reflected back into the foot space; the insulating layer as part of the vacuum cannot absorb and store the radiated heat. The inability to store radiated heat reduces the capability to maintain a warm internal space.
Thus, and as described in detail herein, some of the above issues may be at least partly addressed by the herein disclosed layered insulation pack for a wearable article, where the layered insulation pack includes a perforated layer, a compressible layer, and a reflective layer. The perforated layer may operate as a perforated air communication and retention layer in air communication with an inner body space. The compressible layer may be more compressible than the perforated layer.
In one example, the compressible layer and the perforated layer may comprise a lofted air space to store air even when compressed under the weight of a wearer. Radiated body heat from a foot of a wearer may be reflected by the reflective layer. The radiated body heat and the reflected body heat may warm air in the lofted air space and in the inner body space of the article. Further, warmed air in the inner body space may circulate during movement of the wearer and pass into and out of the lofted air space. Further, the warm air in the lofted air space may act as an insulating layer, limiting conduction of body heat to a cold exterior environment.
As a specific example, and not as a limitation, the layered insulation pack may be positioned in a sole, such as in a midsole, of a boot. In this specific example, the insulation pack comprises a honeycomb perforated layer including a plurality of hexagonal perforations, which are in air communication with the inner body space of the boot. The insulation pack further comprises an insulating layer, which is adhered to and in face-sharing contact with the honeycomb perforated layer. The insulating layer includes a network of fibers which are capable of holding air and are in air communication with the plurality of hexagonal perforations. The insulating layer may be more compressible than the honeycomb layer. The insulation pack may also include a reflective layer, which may be adhered to and in face-sharing contact with the insulating layer and the foam layer.
By providing a layered insulation pack with a lofted air space from the perforated layer, heated air may circulate throughout the inner body space of the footwear. Air retained in the footwear may be warmed by radiated body heat and retained within the perforated and insulating layers. Further, the reflective layer reflects the warmed air (the radiated body heat) back into the lofted air space and the inner body space, thus contributing to warming the wearer's foot. The retention of the warmed air in the lofted air space insulates the wearer from heat loss by reducing the conduction of body heat through the outsole to a cold exterior surface.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The figures are drawn to scale, but such scale is one example and various modifications to sizes, dimensions, and relative positioning may be made, if desired.